Obstetrical forceps are medical instruments comprised of two blades (i.e. the fetal head engaging portions), each connected to a handle by a shank, with a sliding lock between the handle and the shank. The forceps typically grasp the fetal head in a tong-like manner and are used for assisting in the delivery of a baby. When needed, they can be a valuable medical tool to shorten or end the second (expulsion of the fetus) stage of labor, whenever to do so is in the best interest of the mother or the fetus.
Despite the remarkable evolution of this instrument since its introduction in the 1600's, little progress has been made in avoidance of excessive traction forces, in order to prevent injury to the fetal head during a delivery. In fact, when to desist from further extractive efforts is left to the judgment and courage of the obstetrician. Consequently, there is always the risk of a traction force being applied to the forceps that exceeds the limits of safety, with severe head trauma to the baby, resulting in complications ranging from perinatal death, cerebral palsy, and neurological disorders, to mental retardation and behavioral problems.
The above devastating consequences of excessive pull during a forceps delivery, and the resulting medico-legal sequelae, have prompted several attempts over the years to develop devices to measure the compression and traction forces applied to the fetal head during the use of forceps.
Examples of such forceps include U.S. Pat. No. 3,665,925, related to an obstetrical forceps that mechanically indicate the pressure exerted to the fetal head through strain gauges applied to the base of the forceps; U.S. Pat. No. 3,785,381, related to an obstetrical forceps with a pressure sensor arranged on the tip of the fetal engaging portion of the blade; and U.S. Pat. No. 5,649,934, related to an obstetrical forceps with sensing optical bending strains embedded in the shanks. All the above modifications have inherent drawbacks. In particular, the previous inventions are cumbersome and time-consuming to use, which makes it unlikely for a doctor to resort to them, particularly during an emergency delivery. In fact, some of them require calibration prior to their use (U.S. Pat. No. 5,649,934), while others have sensors taped to the blades, gauges attached to the handles, and fastidious cable connections. In addition, these previous inventions may pose problems with sterilization.
Accordingly, there is a need for improved obstetrical forceps that can measure the traction forces applied to the fetal head without the constraints and design drawbacks seen in the prior art and described above.